J. E. Simmons

Neutron spectra at 0° from p—p and p—d collisions at 647 and 800 MeV incident energies

Abstract The p—d spectra show sharp high-energy peaks (≈ 15 MeV FWHM) with integrated yields of 30 and 31 mb/sr, respectively and with lower-energy bumps associated with pion production. The p—p spectra reflect the influence of the Δ(1232) resonance.

Neutron spectra at 0° from (p, n) reactions on 9Be, 12C, and 27Al at 647 and 800 MeV

Abstract The measured cross sections show a narrow high-energy peak (20–30 MeV/ c FWHM ) and a broad bump at lower momenta associated with pion production. Comparison is made to an intranuclear cascade calculation.

Coherent eta -meson production in the reaction pi -+3He--> eta +t.

The reaction {pi}{sup {minus}}+{sup 3}He{r arrow}{eta}+{ital t} has been observed by detecting {eta}{r arrow}2{gamma} decays. The observed forward-angle cross sections vary from {similar to}100 {mu}b/sr at 680 MeV/{ital c} to {similar to}2 {mu}b/sr at 590 MeV/{ital c}. Distorted-wave impulse-approximation calculations reproduce the shape but underestimate the magnitude of the observed cross section. These cross sections are approximately 100 times larger than those for the reaction {ital p}+{ital d}{r arrow}{eta}+{sup 3}He measured at similar {eta} center-of-mass energies.

The measurement of KNN,KLLINpd →nX and p9Be→nX at 800 MeV☆

Abstract The polarization transfer parameters,KNN and KLL, have been measured in p d→ n X and p 9Be→ n X at 0° and 800 MeV. The quasifree p d→ n X values for KNN and KLL are close to the free n-p measured values. The rather large values of KLL demonstrate that this transfer mechanism will provide a useful source of polarized neutrons at medium energies.

The measurement of KNN and KLL in at 800 MeV

Abstract The spin-transfer parameters K NN and K LL have been measured for at 0° and 800 MeV for neutron momenta between 700 and 1200 MeV c . Peak values of K NN and K LL are −0.30 ± 0.05 and −0.5 ± 0.1 respectively. These results are in substantial disagreement with VerWests field theoretic model.

Measurement of KLL and KNN in pd → npp at 500, 650 and 800 MeV

Abstract Measurements of the spin transfer parameters, KNN and KLL, at 500, 650 and 800 MeV are presented for the reaction p d → n pp at 0°. The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction us a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV.

Longitudinal polarization transfer in the D(d,n)3He reaction at 0°

Abstract We have measured the longitudinal neutron polarization in the D( d , n ) 3 He reaction, at θ=0°, for an incident longitudinally polarized deuteron beam. A deuteron energy range of 3.3–14.9 MeV was covered. The polarization transfer from the deuteron to the neutron is found to be large, and the reaction is potentially useful as a source of polarized neutrons.

Differential cross-section for n p elastic scattering in the angular region 50-degrees < Theta* < 180-degrees at 459-MeV

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Differential cross section for n − p elastic scattering in the angular range 51 ° θ * 180 ° at 647.5 MeV

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Measurement of (p,n) and (n,p) reactions on 6Li and 7Li at 800 MeV☆

Abstract The measured 7 Li(p,n), and 6 Li(n,p) cross sections at 0° show a high-energy peak (≈25 MeV/ c FWHM) which we attribute primarily to nuclear charge exchange leading to final states in 7 Be, 6 Be, and 6 He, respectively. By contrast, the 7 Li(n,p) cross section at O° shows a broad weak high-energy peak believed due mostly to break-up processes. At 16°, the 6,7 Li(n,p) cross sections are dominated by quasi-elastic scattering.